BP hopes to contain the spill from its leaking well in the Gulf of Mexico within 24 hours. Its chief operating officer Doug Suttles has said an operation using undersea robots to cut off the fractured pipe and seal it with a cap was launched on Tuesday. It comes as U.S. Attorney General Eric Holder announced that officials had begun criminal and civil investigations into America's worst oil spill. <br/> BP's shares fell sharply on Tuesday after the failure of its previous efforts to "top kill" the leak by pumping mud into the well. <br/> The U.S President Barack Obama described the leak as "the greatest environmental disaster of its kind in our history" and pledged to bring those responsible to justice. <br/>